The components used in electronic equipment, both active and passive, exhibit performance characteristics that vary with speed or operating frequency, voltage, and temperature. Presumably, all components are tested to confirm that they function properly and meet their respective specifications, prior to insertion in a system.
Within a system, individual components may introduce delays that cumulatively affect the system's overall performance. Although one could mathematically combine all of the individual delays in some fashion to predict performance, it would be more accurate to directly measure performance of the system as a whole.
To more precisely predict such performance, two different kinds of parametric testing may be employed. One concerns performance over a predetermined, fixed range. Here, the question is whether the system (or some other unit or subset of the system) can function over the expected range of parameters, such as speed or frequency, voltage, and temperature--essentially a pass/fail system. One goal of this scheme is to determine reliability under worst-case conditions.
A second type of testing permits one to differentiate performance variations usually found among otherwise-identical components or sub-systems. Given the variation in performance of individual components discussed above, one could expect a similar variation in the performance of an entire system.
Typically, parametric testing is performed manually or semi-automatically using special tools or test sets. Either of these approaches is costly. Manual testing requires documentation and training. In the case of semi-automatic testing, an investment in specially-designed test apparatus may not be cost-justified where the sales volume is low.
It would be desirable to provide a method and an apparatus to automatically test the overall performance of a system under variations of speed, voltage, and/or temperature. It is also desirable to provide a method that could be used to gradate individual units of the same kinds of system, again based on one or more performance specifications and/or parameters.
In addition to testing, it would also be desirable to detect system performance failures.